How can the Clarity Plug-In Hybrid produce 212 hp?

I don't know exactly where that value comes from in the Clarity, but at least based on the diagram of the electric drivetrain that the car displays (and the description thereof in the manual) it is indeed capable of powering the wheels with both the gasoline engine (using the mechanical linkage) and the 181HP electric motor at the same time. In this state it would make sense that the gasoline engine can't be supplying in excess of 103HP from its ICE to the combination of the generator and wheels (assuming it can indeed run both at the same time at all, which I'm not sure of), then you're dealing with some combination of the theoretical 121HP that the main motor can produce from the batteries and theoretical 103HP that the ICE can produce on its own, which (apparently) adds up to a maximum of 212 HP in practice rather than 224HP (which isn't particularly surprising).

Assuming this is in fact correct, it would only be possible to achieve the maximum horsepower output of the car at speeds above 50mph (possibly way above 50mph, since the peak power output of the ICE should be at a very high speed and I've been told that the mechanical transmission is a fixed gear ratio so it can't downshift to increase RPMs for a given speed).

 

That chart didn't clearly show the other option. In the paper, figure 20 shows the engine drive mode relative to the road load. The red line is the engine output. The star is when the engine output is the same as the road load. If the load is less than the engine output then the battery will charge from regeneration . If the load is greater, the right of the star, the battery will output to the ev motor to make up the difference. That is where the outputs combine.

 

The Clarity PHEV has the same 181hp traction motor as the Accord Hybrid.
https://automobiles.honda.com/clarity-plug-in-hybrid/specs-features-trim-comparison

The difference is that the Accord has a larger ICE. Perhaps Honda reduces the power output of the traction motor in the Accord when in hybrid mode such that it gets the same combined maximum power rating as the Clarity. Would make sense in order to preserve the charge in the smaller Accord Hybrid battery.

 

The Accord hybrid only has a small 1.7 kWh battery, which can provide only a small number of horses from the traction motor by itself, unlike the Clarity which can get 120 horses from the battery alone. To get to 181 hp, it needs to be supplemented by the ICE. It can get to 212 peak hp by also engaging the clutch so it can't provide the total 212 hp unless going over 50 mph or so. The Accord depends mostly on the ICE to generate sufficient electrons to power the traction motor. It would have to work a lot harder than the Clarity ICE to utilize the full 181 hp of the traction motor. That's the reason the Accord has a more powerful ICE, to compensate for a battery one tenth the size of the Clarity's.

 

From Honda's specs it appears that the electric motor in the Clarity is good for 181 HP (and 232 lb-ft torque) by itself. As @insightman clarified, it is not the exact same motor as the Accord hybrid--as the variation in the Accord that does not have rare-earth metals may not be able to sustain the temperatures that an EV primary vehicle would need--but both traction motors are rated for the same output.

The total system HP of 212 is in combination with the ICE.

I agree with you that the smaller battery in the Accord hybrid probably is a factor in how it gets the same peak HP as the Clarity even though the Accord has a larger ICE. My guess is that the ICE takes a bigger load in the Accord to reduce the drain on the smaller battery.

 

I would add that it certainly feels like 181HP and 232 lb-ft of torque when accelerating in EV only mode. 121HP would not be able to provide the oomph that we experience for a car this heavy.

 

Honda and Hyundai claimed 50% more power by using rectangular winding instead of the circular winding for their motor.

 

I assume it's triggered by flooring the gas pedal, like any other all-out mode. The car will put out as much power as it's able at the given speed. How many actual horsepower that at the wheels is will depend on your speed (and probably other factors), just like in a pure-ICE vehicle. Being an EV, in Eco mode if you don't push past the breakover, it will be limited by the output of the battery (which may vary with temperature), and will be virtually flat. If you floor it in non-Eco modes, it will output as much power as the combination of the battery and ICE are able at whatever speed you're traveling at. At lower speeds, this will presumably be capped by the electric motor. At higher speeds it may involve the mechanical transmission as well.

One comment, it's also theoretically possible that the electric motor is capable of higher-than-rated output for brief periods before the cooling capability/thermal mass limits it. I'm assuming that's not where the 212hp number comes from, but it theoretically could be.

Respectfully, a "verbose" mode is kind of silly to even imagine in a consumer vehicle, let alone a 4-door family sedan--and I'm an engineer who would probably have it up as the default display.

An Accord does not have a "verbose" display that shows you what the logic behind the EFI timing is, or what torque calculations it's using to decide whether to up or downshift, or what the exact torque or horsepower output is at the moment and how it's achieving that; it never has, and it never will. You get a speedometer, a tach, and maybe an indication of what gear it's in. 99.99% of owners simply do not care, 99% would not be able to interpret the information even if they did, and some measurable fraction would bring the display up, not know what it meant, and misinterpret the information.

If you want any more information than that, as with any other car you're going to have to instrument it yourself.

There is already a display that shows whether power is coming from or going to the battery, coming from the ICE or not, and whether the mechanical transmission is engaged or not. That's really about as detailed as I would ever expect to see in a non-performance consumer vehicle. A hard kW number for the electric portions where it's easily measured would be nice (a la earlier Volts, though that was pulled from Gen2), but that's about the realistic limit.

 

I’d be happy with just an idiot light on the DDI that showed up when the ICE was on.

 

I think it's more important what torque you are getting. Since torque is important for low speed acceleration and highway passing. Peak horsepower is more for top speed driving. Also, you could get one of those ODB devices and a phone app (such as the Torque app) to read the system stuff. Not sure what you can get from a Clarity, but maybe the ICE RPM, which would be interesting. Oddly enough, if one of these apps supported Android Auto/Apple Carplay, then you can have those displayed on your screen.

 

As ab13 mentions, this is the kind of thing that people have done in other cars with an OBD port. I find it unlikely there will ever be anything similar to the ODB-based dashboard displays people get for conventional vehicles, but I know people have managed to extract fairly detailed information about what the Volt is doing electrically via either the OBD port or hacking the CAN bus, so something similar should be possible with the Clarity.

That said, does the Clarity even have an OBD-II port? I haven't looked, but attaching a dongle would be fun if it did.

 

When I tested 0-60 in the Volt 1, the i3 Rex, and Clarity, in EV only mode I saw 12-13s for Clarity, 10s for Volt and 7.8 seconds for i3.

This is right inline with Clarity having only 120 hp in EV only mode, 150 hp for the Volt, and about 170 hp for the i3.

With the Clarity in mixed mode it was faster than the Volt around 8.5 seconds which is inline with it having 212 hp.

 

PS, the main electric motor is 180 hp, but it needs electricity generated from the Genset to reach that level. The battery doesn't appear capable of delivering that much power.

 

I won't go as far as to say it was closer to 212 than 180, either could probably do that 0-60 run depending on assumptions and measurement accuracy, my main differentiator here was the 120 hp battery only vs 180+ combined mode. They battery is limiting traction motor performance. I will do a test later to see if the gear comes on, but really I need better equipment to measure that like an IMU.

 

Going back and looking at my notes, the Clarity was 9 sec to 60, which would likely put it closer to 180 hp, but again, it was a few runs using Torque Pro, so nothing more than informational. Would need to dig more in depth to see if Honda's claim of 212 is valid, my guess is it is a limited test case.